Interfacial water structure is key to many chemical and physical processes.  It can be probed by vibrational sum-frequency generation (vSFG) spectroscopy as well as ultrafast time-resolved vSFG. However, a more complete microscopic understanding of spectroscopic and dynamic response requires additional techniques such as molecular dynamics simulations.  vSFG spectroscopy has demonstrated that silica interfacial water structure is most sensitive to ions at pH=6-8, correlating with the known salt and pH dependence of silica surface reactivity.   The ultrafast relaxation of the OH stretch vibration also shows a strong dependence on ionic strength near ph=6.  Whether these effects are due to the reduction in the Debye length and sampling depth of vSFG, or because of changes in the local hydrogen bonding environment caused by the electrolyte is not yet clear.  The combination of molecular dynamics simulations with spectroscopic and time-resolved vSFG experiments on aqueous Al<sub>2</sub>O<sub>3</sub> interfaces sheds light on the ongoing debate on the role of ions in interfacial water structure and whether the observed behavior is specific to silica/water interfaces or can be generalized to other interfaces between aqueous solutions and mineral oxides.

Combining vibrational sum frequency generation and molecular dynamics simulations to probe the effect of ions on solvent structure at mineral- aqueous interfaces

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.